lkml.org 
[lkml]   [2019]   [Sep]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH AUTOSEL 4.19 015/167] x86/kvm/lapic: preserve gfn_to_hva_cache len on cache reinit
Date
From: Vitaly Kuznetsov <vkuznets@redhat.com>

[ Upstream commit a7c42bb6da6b1b54b2e7bd567636d72d87b10a79 ]

vcpu->arch.pv_eoi is accessible through both HV_X64_MSR_VP_ASSIST_PAGE and
MSR_KVM_PV_EOI_EN so on migration userspace may try to restore them in any
order. Values match, however, kvm_lapic_enable_pv_eoi() uses different
length: for Hyper-V case it's the whole struct hv_vp_assist_page, for KVM
native case it is 8. In case we restore KVM-native MSR last cache will
be reinitialized with len=8 so trying to access VP assist page beyond
8 bytes with kvm_read_guest_cached() will fail.

Check if we re-initializing cache for the same address and preserve length
in case it was greater.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/lapic.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ccf5a04de94c3..973a244081d34 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2631,14 +2631,22 @@ int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 reg, u64 *data)
int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data, unsigned long len)
{
u64 addr = data & ~KVM_MSR_ENABLED;
+ struct gfn_to_hva_cache *ghc = &vcpu->arch.pv_eoi.data;
+ unsigned long new_len;
+
if (!IS_ALIGNED(addr, 4))
return 1;

vcpu->arch.pv_eoi.msr_val = data;
if (!pv_eoi_enabled(vcpu))
return 0;
- return kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.pv_eoi.data,
- addr, len);
+
+ if (addr == ghc->gpa && len <= ghc->len)
+ new_len = ghc->len;
+ else
+ new_len = len;
+
+ return kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, addr, new_len);
}

void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
--
2.20.1
\
 
 \ /
  Last update: 2019-09-03 18:26    [W:1.271 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site